Further improvement for chroma mode coding

ABSTRACT

A method, system, and non-transitory computer readable medium is provided for decoding video data. Video data comprising a chroma component having a first nominal angle and first delta angles and a luma component having a second nominal angle and second delta angles is received, wherein the first delta angles are dependent on the second delta angles. The first delta angle values corresponding to the first delta angles are parsed or derived based at least on second delta values corresponding to the second delta angles, wherein the first delta angle values are derived from one or more nominal angles associated with one or more sample positions corresponding to one or more luma blocks. A prediction mode associated with the chroma component based on a nominal mode of a corresponding luma block is entropy-coded. The video data is decoded based on the first delta angle values corresponding to the first delta angles.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a Continuation Application of U.S. application Ser.No. 17/873,761, filed on Jul. 26, 2022, which is a ContinuationApplication of U.S. application Ser. No. 16/993,876, filed on Aug. 14,2020, now U.S. Pat. No. 11,432,006, issued on Aug. 30, 2022, theentireties of which are incorporated herein by reference.

FIELD

This disclosure relates generally to field of data processing, and moreparticularly to video encoding and/or decoding.

BACKGROUND

AOMedia Video 1 (AV1) is an open video coding format designed for videotransmissions over the Internet. It was developed as a successor to VP9by the Alliance for Open Media (AOMedia), a consortium founded in 2015that includes semiconductor firms, video on demand providers, videocontent producers, software development companies and web browservendors. In AV1, there is a total 56 directional angles, of which 8 arenominal angles and the remainder are specified as a delta from thenominal angles.

SUMMARY

Embodiments relate to a method, system, and computer readable medium forencoding and/or decoding video data. According to one aspect, a methodfor encoding and/or decoding video data is provided. The method mayinclude receiving video data comprising a chroma component having afirst nominal angle and first delta angles and a luma component having asecond nominal angle and second delta angles, wherein the first deltaangles are dependent on the second delta angles; parsing or derivingfirst delta angle values corresponding to the first delta angles basedat least on second delta values corresponding to the second deltaangles, wherein the first delta angle values are derived from one ormore nominal angles associated with one or more sample positionscorresponding to one or more luma blocks; entropy-coding of a predictionmode associated with the chroma component based on a nominal mode of acorresponding luma block; and decoding the video data based on the firstdelta angle values corresponding to the first delta angles.

According to another aspect, a computer system for encoding and/ordecoding video data is provided. The computer system may include one ormore computer-readable non-transitory storage media configured to storecomputer program code and one or more computer processors configured toaccess said computer program code and operate as instructed by saidcomputer program code. The program code may include receiving codeconfigured to cause the one or more computer processors to receive videodata comprising a chroma component having a first nominal angle andfirst delta angles and a luma component having a second nominal angleand second delta angles, wherein the first delta angles are dependent onthe second delta angles; parsing or deriving code configured to causethe one or more computer processors to parse or derive first delta anglevalues corresponding to the first delta angles based at least on seconddelta values corresponding to the second delta angles; entropy codeconfigured to cause the one or more computer processors to entropy-codea prediction mode associated with the chroma component based on anominal mode of a corresponding luma block; and decoding code configuredto cause the one or more computer processors to decode the video databased on the first delta angle values corresponding to the first deltaangles.

According to yet another aspect, a non-transitory computer readablemedium for encoding and/or decoding video data is provided. Thenon-transitory computer readable medium may include a computer programfor decoding video data, the computer program configured to cause one ormore computer processors to receive video data comprising a chromacomponent having a first nominal angle and first delta angles and a lumacomponent having a second nominal angle and second delta angles, whereinthe first delta angles are dependent on the second delta angles; parseor derive first delta angle values corresponding to the first deltaangles based at least on second delta values corresponding to the seconddelta angles; wherein the first delta angle values are derived from oneor more nominal angles associated with one or more sample positionscorresponding to one or more luma blocks; entropy-code of a predictionmode associated with the chroma component based on a nominal mode of acorresponding luma block; and decode the video data based on the firstdelta angle values corresponding to the first delta angles.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other objects, features and advantages will become apparentfrom the following detailed description of illustrative embodiments,which is to be read in connection with the accompanying drawings. Thevarious features of the drawings are not to scale as the illustrationsare for clarity in facilitating the understanding of one skilled in theart in conjunction with the detailed description. In the drawings:

FIG. 1 illustrates a networked computer environment according to atleast one embodiment;

FIG. 2 is a diagram of the nominal angles of AV1, according to at leastone embodiment;

FIG. 3 is an operational flowchart illustrating the steps carried out bya program that codes video data, according to at least one embodiment;

FIG. 4 is a block diagram of internal and external components ofcomputers and servers depicted in FIG. 1 according to at least oneembodiment;

FIG. 5 is a block diagram of an illustrative cloud computing environmentincluding the computer system depicted in FIG. 1 , according to at leastone embodiment; and

FIG. 6 is a block diagram of functional layers of the illustrative cloudcomputing environment of FIG. 5 , according to at least one embodiment.

DETAILED DESCRIPTION

Detailed embodiments of the claimed structures and methods are disclosedherein; however, it can be understood that the disclosed embodiments aremerely illustrative of the claimed structures and methods that may beembodied in various forms. Those structures and methods may, however, beembodied in many different forms and should not be construed as limitedto the exemplary embodiments set forth herein. Rather, these exemplaryembodiments are provided so that this disclosure will be thorough andcomplete and will fully convey the scope to those skilled in the art. Inthe description, details of well-known features and techniques may beomitted to avoid unnecessarily obscuring the presented embodiments.

Embodiments relate generally to the field of data processing, and moreparticularly to video encoding and decoding. The following describedexemplary embodiments provide a system, method and computer program to,among other things, encode and/or decode video data using delta anglevalues derived from nominal angle values. Therefore, some embodimentshave the capacity to improve the field of computing by not requiringevery delta angle to be signaled and allowing for on-the-flycalculations of delta angle values.

As previously described, AOMedia Video 1 (AV1) is an open video codingformat designed for video transmissions over the Internet. It wasdeveloped as a successor to VP9 by the Alliance for Open Media(AOMedia), a consortium founded in 2015 that includes semiconductorfirms, video on demand providers, video content producers, softwaredevelopment companies and web browser vendors. In AV1, there is a total56 directional angles, of which 8 are nominal angles and the remainderare specified as a delta from the nominal angles. However, both thenominal angles and the delta angles of all directional modes aresignalled for chroma component, regardless of the collocated lumaprediction modes. Additionally, delta angles are allowed for both lumaand chroma intra prediction modes, but the correlation of the deltaangles between luma and chroma component is not used. It may beadvantageous, therefore, to derive delta angle values for the chromacomponent based on nominal angles from the luma component instead ofsignaling all 56 angle values.

Aspects are described herein with reference to flowchart illustrationsand/or block diagrams of methods, apparatus (systems), and computerreadable media according to the various embodiments. It will beunderstood that each block of the flowchart illustrations and/or blockdiagrams, and combinations of blocks in the flowchart illustrationsand/or block diagrams, can be implemented by computer readable programinstructions.

Referring now to FIG. 1 , a functional block diagram of a networkedcomputer environment illustrating a video coding system 100 (hereinafter“system”) for encoding and/or decoding video data using delta anglesderived from nominal angles. It should be appreciated that FIG. 1provides only an illustration of one implementation and does not implyany limitations with regard to the environments in which differentembodiments may be implemented. Many modifications to the depictedenvironments may be made based on design and implementationrequirements.

The system 100 may include a computer 102 and a server computer 114. Thecomputer 102 may communicate with the server computer 114 via acommunication network 110 (hereinafter “network”). The computer 102 mayinclude a processor 104 and a software program 108 that is stored on adata storage device 106 and is enabled to interface with a user andcommunicate with the server computer 114. As will be discussed belowwith reference to FIG. 4 the computer 102 may include internalcomponents 800A and external components 900A, respectively, and theserver computer 114 may include internal components 800B and externalcomponents 900B, respectively. The computer 102 may be, for example, amobile device, a telephone, a personal digital assistant, a netbook, alaptop computer, a tablet computer, a desktop computer, or any type ofcomputing devices capable of running a program, accessing a network, andaccessing a database.

The server computer 114 may also operate in a cloud computing servicemodel, such as Software as a Service (SaaS), Platform as a Service(PaaS), or Infrastructure as a Service (IaaS), as discussed below withrespect to FIGS. 6 and 7 . The server computer 114 may also be locatedin a cloud computing deployment model, such as a private cloud,community cloud, public cloud, or hybrid cloud.

The server computer 114, which may be used for encoding video data isenabled to run a Video Coding Program 116 (hereinafter “program”) thatmay interact with a database 112. The Video Coding Program method isexplained in more detail below with respect to FIG. 3 . In oneembodiment, the computer 102 may operate as an input device including auser interface while the program 116 may run primarily on servercomputer 114. In an alternative embodiment, the program 116 may runprimarily on one or more computers 102 while the server computer 114 maybe used for processing and storage of data used by the program 116. Itshould be noted that the program 116 may be a standalone program or maybe integrated into a larger video coding program.

It should be noted, however, that processing for the program 116 may, insome instances be shared amongst the computers 102 and the servercomputers 114 in any ratio. In another embodiment, the program 116 mayoperate on more than one computer, server computer, or some combinationof computers and server computers, for example, a plurality of computers102 communicating across the network 110 with a single server computer114. In another embodiment, for example, the program 116 may operate ona plurality of server computers 114 communicating across the network 110with a plurality of client computers. Alternatively, the program mayoperate on a network server communicating across the network with aserver and a plurality of client computers.

The network 110 may include wired connections, wireless connections,fiber optic connections, or some combination thereof. In general, thenetwork 110 can be any combination of connections and protocols thatwill support communications between the computer 102 and the servercomputer 114. The network 110 may include various types of networks,such as, for example, a local area network (LAN), a wide area network(WAN) such as the Internet, a telecommunication network such as thePublic Switched Telephone Network (PSTN), a wireless network, a publicswitched network, a satellite network, a cellular network (e.g., a fifthgeneration (5G) network, a long-term evolution (LTE) network, a thirdgeneration (3G) network, a code division multiple access (CDMA) network,etc.), a public land mobile network (PLMN), a metropolitan area network(MAN), a private network, an ad hoc network, an intranet, a fiberoptic-based network, or the like, and/or a combination of these or othertypes of networks.

The number and arrangement of devices and networks shown in FIG. 1 areprovided as an example. In practice, there may be additional devicesand/or networks, fewer devices and/or networks, different devices and/ornetworks, or differently arranged devices and/or networks than thoseshown in FIG. 1 . Furthermore, two or more devices shown in FIG. 1 maybe implemented within a single device, or a single device shown in FIG.1 may be implemented as multiple, distributed devices. Additionally, oralternatively, a set of devices (e.g., one or more devices) of system100 may perform one or more functions described as being performed byanother set .of devices of system 100.

Referring now to FIG. 2 , a diagram 200 illustrating nominal angles ofAV1 is depicted. In AV1, there are 8 nominal angles between 45 and 207degrees that may include V_PRED, H_PRED, D45_PRED, D135_PRED, D113_PRED,D157_PRED, D203_PRED, and D67_PRED. For each nominal angle, there may be7 finer angles, such that AV1 may have 56 directional angles in total.The prediction angle may be represented by a nominal intra angle plus anangle delta, which is −3˜3 multiplies the step size of 3 degrees. Thedelta angles may not need to be signaled by the chroma component but mayinstead by derived according to the corresponding luma intra predictionmodes.

In one or more embodiments, when the current chroma intra predictionmode is directional intra prediction mode and the nominal angle of thechroma intra prediction mode is equal to that of corresponding lumaintra prediction mode, then the delta angle of the chroma component maybe set equal to the delta angle of luma intra prediction mode.Otherwise, the delta angle of the chroma component may be set equal to0.

In one or more embodiments, the delta angle of the chroma component maybe set equal to the delta angle of the luma component, regardless ofwhether the nominal mode between luma and chroma is same or not.

In one or more embodiments, when the current chroma intra predictionmode is directional intra prediction mode and the nominal angle of thechroma intra prediction mode is equal to that of corresponding lumaintra prediction mode, then the delta angle of the chroma component maybe set equal to the delta angle of luma intra prediction mode.Otherwise, when the nominal angle of the chroma intra prediction mode isequal to the left/above neighboring modes of the corresponding lumablock, then the delta angle of the chroma component may be set equal tothat of left/above neighboring modes of the corresponding luma block.Otherwise, the delta angle of the chroma component may be set equal to0.

In one or more embodiments, when semi-decoupled partitioning is applied,there may be multiple luma blocks associated with one chroma block.Therefore, multiple sample positions may be pre-defined, and the deltaangles and nominal angles associated with these positions for predictingthe co-located luma block may be identified. One or more of theseidentified nominal angles and delta angles may be used to derive thedelta angles of current chroma block. In one example, the pre-definedsample positions may include the top-left and/or the center/middlesamples. In another example, the pre-defined sample positions mayinclude the four corner samples and the center/middle sample. In anotherexample, the delta angles that may be used most frequently among theidentified prediction modes may be used to derive the derive the deltaangles of the chroma component. In another example, the pre-definedsample positions may include two selected positions of the four cornersamples and one center/middle sample. In another example, thepre-defined sample positions may include three selected positions of thefour corner samples and one center/middle sample.

In one or more embodiments, when the current chroma intra predictionmode is directional intra prediction mode and the nomimal angle of thechroma intra prediction mode is equal to that of corresponding lumaintra prediction mode, then the delta angle of the chroma component maybe set equal to the delta angle of luma intra prediction mode.Otherwise, when the nominal angle of the chroma intra prediction mode isequal to the left/above neighboring modes of current chroma block, thenthe delta angle of the chroma component may be set equal to that ofleft/above neighboring modes of current chroma block. Otherwise, thedelta angle of the chroma component may be set equal to 0.

The delta angle of the corresponding luma block may be used for theentropy coding of the delta angles of chroma intra prediction modes. Inone or embodiments, the delta angle of the co-located luma blocks may beused as the context for the entropy coding of the delta angles of thechroma component. In one or more embodiments, the delta angle of theneighboring chroma blocks is used as the context for the entropy codingof the delta angles of the chroma component. In one or embodiments,instead of signaling the delta angles of the current chroma block, theabsolute difference between delta angles of chroma blocks and thecorresponding luma blocks may be signaled for the entropy coding of thechroma intra prediction modes. In one or more embodiments, the aboveembodiments are applied only when the nominal mode between luma andchroma may be same or when the absolute difference of prediction anglesbetween these two modes is within a given threshold.

According to one or more embodiments, for entropy coding of the chromaintra prediction modes, a first flag may be signaled to indicate whetheror not the current mode is chroma-from-luma (CfL). If the first flag issignaled as a value indicating CfL is not being used, a second flag maybe signaled to indicate whether the current mode may be equal to thenominal mode of the corresponding luma block. If the current mode isequal to the nominal mode of the corresponding luma block, current modeis directional mode, and delta angles are allowed, then a third flag maybe signaled to indicate the index of the delta angles. Otherwise, thethird flag is signaled to indicate which of the remaining nominal modescurrent mode is. If the first flag is signaled as a value indicating CfLis not being used, the parameters of the CfL mode may be furthersignaled.

According to one or more embodiments, for entropy coding of the chromaintra prediction modes, the first flag may be signaled to indicatewhether current mode may be equal to the nominal mode of thecorresponding luma block or CfL mode. If the first flag is signaled as avalue indicating the current mode is equal to the nominal mode of thecorresponding luma block or CfL mode, the second flag may be signaled toindicate which of the two modes may be the current mode. If the currentmode is equal to the nominal mode of the corresponding luma block, thecurrent mode is directional mode, and delta angles are allowed, then theindex of the delta angles may be further signaled. If the current modeis CfL mode, the parameters of the CfL mode may be further signaled. Ifthe first flag is signaled as a value indicating the current mode is notequal to the nominal mode of the corresponding luma block or CfL mode,the second flag may be signaled to indicate which of the remainingnominal modes may be applied for the current chroma block.

In one or more embodiments, the first delta angle values may beentropy-coded based on using a delta angle of co-located luma blocks asa context in response to the nominal angle of the chroma component andthe nominal angle of the luma component being the same or close to eachother. The nominal angles may be close to each other when a differenceof the between the nominal angles is less than or equal to 2 degrees.The delta angle values may be entropy-coded based on using a delta angleof co-located luma blocks as a context or based on using a delta angleof neighboring chroma blocks as a context.

It may be appreciated that, in one or more embodiments, the delta anglesof luma and chroma blocks may use the separate contexts for entropycoding instead of sharing the same context among the delta angles of theluma and chroma blocks

Referring now to FIG. 3 , an operational flowchart illustrating thesteps of a method 300 for encoding and/or decoding video data isdepicted. In some implementations, one or more process blocks of FIG. 3may be performed by the computer 102 (FIG. 1 ) and the server computer114 (FIG. 1 ). In some implementations, one or more process blocks ofFIG. 3 may be performed by another device or a group of devices separatefrom or including the computer 102 and the server computer 114.

At 302, the method 300 includes receiving video data including (1) achroma component having a first nominal angle and first delta angles and(2) a luma component having a second nominal angle and second deltaangles. The first delta angles are dependent on the second delta angles.

At 304, the method 300 includes parsing first delta angle values for thefirst delta angles based on at least an intra prediction mode associatedwith the luma component.

At 306, the method 300 includes encoding and/or decoding the video databased on the first delta angle values corresponding to the first deltaangles.

It may be appreciated that FIG. 3 provides only an illustration of oneimplementation and does not imply any limitations with regard to howdifferent embodiments may be implemented. Many modifications to thedepicted environments may be made based on design and implementationrequirements.

FIG. 4 is a block diagram 400 of internal and external components ofcomputers depicted in FIG. 1 in accordance with an illustrativeembodiment. It should be appreciated that FIG. 4 provides only anillustration of one implementation and does not imply any limitationswith regard to the environments in which different embodiments may beimplemented. Many modifications to the depicted environments may be madebased on design and implementation requirements.

Computer 102 (FIG. 1 ) and server computer 114 (FIG. 1 ) may includerespective sets of internal components 800A,B and external components900A,B illustrated in FIG. 4 . Each of the sets of internal components800 include one or more processors 820, one or more computer-readableRAMs 822 and one or more computer-readable ROMs 824 on one or more buses826, one or more operating systems 828, and one or morecomputer-readable tangible storage devices 830.

Processor 820 is implemented in hardware, firmware, or a combination ofhardware and software. Processor 820 is a central processing unit (CPU),a graphics processing unit (GPU), an accelerated processing unit (APU),a microprocessor, a microcontroller, a digital signal processor (DSP), afield-programmable gate array (FPGA), an application-specific integratedcircuit (ASIC), or another type of processing component. In someimplementations, processor 820 includes one or more processors capableof being programmed to perform a function. Bus 826 includes a componentthat permits communication among the internal components 800A,B.

The one or more operating systems 828, the software program 108 (FIG. 1) and the Video Coding Program 116 (FIG. 1 ) on server computer 114(FIG. 1 ) are stored on one or more of the respective computer-readabletangible storage devices 830 for execution by one or more of therespective processors 820 via one or more of the respective RAMs 822(which typically include cache memory). In the embodiment illustrated inFIG. 4 , each of the computer-readable tangible storage devices 830 is amagnetic disk storage device of an internal hard drive. Alternatively,each of the computer-readable tangible storage devices 830 is asemiconductor storage device such as ROM 824, EPROM, flash memory, anoptical disk, a magneto-optic disk, a solid state disk, a compact disc(CD), a digital versatile disc (DVD), a floppy disk, a cartridge, amagnetic tape, and/or another type of non-transitory computer-readabletangible storage device that can store a computer program and digitalinformation.

Each set of internal components 800A,B also includes a R/W drive orinterface 832 to read from and write to one or more portablecomputer-readable tangible storage devices 936 such as a CD-ROM, DVD,memory stick, magnetic tape, magnetic disk, optical disk orsemiconductor storage device. A software program, such as the softwareprogram 108 (FIG. 1 ) and the Video Coding Program 116 (FIG. 1 ) can bestored on one or more of the respective portable computer-readabletangible storage devices 936, read via the respective RAY drive orinterface 832 and loaded into the respective hard drive 830.

Each set of internal components 800A,B also includes network adapters orinterfaces 836 such as a TCP/IP adapter cards; wireless Wi-Fi interfacecards; or 3G, 4G, or 5G wireless interface cards or other wired orwireless communication links. The software program 108 (FIG. 1 ) and theVideo Coding Program 116 (FIG. 1 ) on the server computer 114 (FIG. 1 )can be downloaded to the computer 102 (FIG. 1 ) and server computer 114from an external computer via a network (for example, the Internet, alocal area network or other, wide area network) and respective networkadapters or interfaces 836. From the network adapters or interfaces 836,the software program 108 and the Video Coding Program 116 on the servercomputer 114 are loaded into the respective hard drive 830. The networkmay comprise copper wires, optical fibers, wireless transmission,routers, firewalls, switches, gateway computers and/or edge servers.

Each of the sets of external components 900A,B can include a computerdisplay monitor 920, a keyboard 930, and a computer mouse 934. Externalcomponents 900A,B can also include touch screens, virtual keyboards,touch pads, pointing devices, and other human interface devices. Each ofthe sets of internal components 800A,B also includes device drivers 840to interface to computer display monitor 920, keyboard 930 and computermouse 934. The device drivers 840, R/W drive or interface 832 andnetwork adapter or interface 836 comprise hardware and software (storedin storage device 830 and/or ROM 824).

It is understood in advance that although this disclosure includes adetailed description on cloud computing, implementation of the teachingsrecited herein are not limited to a cloud computing environment. Rather,some embodiments are capable of being implemented in conjunction withany other type of computing environment now known or later developed.

Cloud computing is a model of service delivery for enabling convenient,on-demand network access to a shared pool of configurable computingresources (e.g. networks, network bandwidth, servers, processing,memory, storage, applications, virtual machines, and services) that canbe rapidly provisioned and released with minimal management effort orinteraction with a provider of the service. This cloud model may includeat least five characteristics, at least three service models, and atleast four deployment models.

Characteristics are as follows:

On-demand self-service: a cloud consumer can unilaterally provisioncomputing capabilities, such as server time and network storage, asneeded automatically without requiring human interaction with theservice's provider.

Broad network access: capabilities are available over a network andaccessed through standard mechanisms that promote use by heterogeneousthin or thick client platforms (e.g., mobile phones, laptops, and PDAs).

Resource pooling: the provider's computing resources are pooled to servemultiple consumers using a multi-tenant model, with different physicaland virtual resources dynamically assigned and reassigned according todemand. There is a sense of location independence in that the consumergenerally has no control or knowledge over the exact location of theprovided resources but may be able to specify location at a higher levelof abstraction (e.g., country, state, or datacenter).

Rapid elasticity: capabilities can be rapidly and elasticallyprovisioned, in some cases automatically, to quickly scale out andrapidly released to quickly scale in. To the consumer, the capabilitiesavailable for provisioning often appear to be unlimited and can bepurchased in any quantity at any time.

Measured service: cloud systems automatically control and optimizeresource use by leveraging a metering capability at some level ofabstraction appropriate to the type of service (e.g., storage,processing, bandwidth, and active user accounts). Resource usage can bemonitored, controlled, and reported providing transparency for both theprovider and consumer of the utilized service.

Service Models are as follows:

Software as a Service (SaaS): the capability provided to the consumer isto use the provider's applications running on a cloud infrastructure.The applications are accessible from various client devices through athin client interface such as a web browser (e.g., web-based e-mail).The consumer does not manage or control the underlying cloudinfrastructure including network, servers, operating systems, storage,or even individual application capabilities, with the possible exceptionof limited user-specific application configuration settings.

Platform as a Service (PaaS): the capability provided to the consumer isto deploy onto the cloud infrastructure consumer-created or acquiredapplications created using programming languages and tools supported bythe provider. The consumer does not manage or control the underlyingcloud infrastructure including networks, servers, operating systems, orstorage, but has control over the deployed applications and possiblyapplication hosting environment configurations.

Infrastructure as a Service (IaaS): the capability provided to theconsumer is to provision processing, storage, networks, and otherfundamental computing resources where the consumer is able to deploy andrun arbitrary software, which can include operating systems andapplications. The consumer does not manage or control the underlyingcloud infrastructure but has control over operating systems, storage,deployed applications, and possibly limited control of select networkingcomponents (e.g., host firewalls).

Deployment Models are as follows:

Private cloud: the cloud infrastructure is operated solely for anorganization. It may be managed by the organization or a third party andmay exist on-premises or off-premises.

Community cloud: the cloud infrastructure is shared by severalorganizations and supports a specific community that has shared concerns(e.g., mission, security requirements, policy, and complianceconsiderations). It may be managed by the organizations or a third partyand may exist on-premises or off-premises.

Public cloud: the cloud infrastructure is made available to the generalpublic or a large industry group and is owned by an organization sellingcloud services.

Hybrid cloud: the cloud infrastructure is a composition of two or moreclouds (private, community, or public) that remain unique entities butare bound together by standardized or proprietary technology thatenables data and application portability (e.g., cloud bursting forload-balancing between clouds).

A cloud computing environment is service oriented with a focus onstatelessness, low coupling, modularity, and semantic interoperability.At the heart of cloud computing is an infrastructure comprising anetwork of interconnected nodes.

Referring to FIG. 5 , illustrative cloud computing environment 500 isdepicted. As shown, cloud computing environment 500 comprises one ormore cloud computing nodes 10 with which local computing devices used bycloud consumers, such as, for example, personal digital assistant (PDA)or cellular telephone 54A, desktop computer 54B, laptop computer 54C,and/or automobile computer system 54N may communicate. Cloud computingnodes 10 may communicate with one another. They may be grouped (notshown) physically or virtually, in one or more networks, such asPrivate, Community, Public, or Hybrid clouds as described hereinabove,or a combination thereof. This allows cloud computing environment 600 tooffer infrastructure, platforms and/or software as services for which acloud consumer does not need to maintain resources on a local computingdevice. It is understood that the types of computing devices 54A-N shownin FIG. 5 are intended to be illustrative only and that cloud computingnodes 10 and cloud computing environment 500 can communicate with anytype of computerized device over any type of network and/or networkaddressable connection (e.g., using a web browser).

Referring to FIG. 6 , a set of functional abstraction layers 600provided by cloud computing environment 500 (FIG. 5 ) is shown. Itshould be understood in advance that the components, layers, andfunctions shown in FIG. 6 are intended to be illustrative only andembodiments are not limited thereto. As depicted, the following layersand corresponding functions are provided:

Hardware and software layer 60 includes hardware and softwarecomponents. Examples of hardware components include: mainframes 61; RISC(Reduced Instruction Set Computer) architecture based servers 62;servers 63; blade servers 64; storage devices 65; and networks andnetworking components 66. In some embodiments, software componentsinclude network application server software 67 and database software 68.

Virtualization layer 70 provides an abstraction layer from which thefollowing examples of virtual entities may be provided: virtual servers71; virtual storage 72; virtual networks 73, including virtual privatenetworks; virtual applications and operating systems 74; and virtualclients 75.

In one example, management layer 80 may provide the functions describedbelow. Resource provisioning 81 provides dynamic procurement ofcomputing resources and other resources that are utilized to performtasks within the cloud computing environment. Metering and Pricing 82provide cost tracking as resources are utilized within the cloudcomputing environment, and billing or invoicing for consumption of theseresources. In one example, these resources may comprise applicationsoftware licenses. Security provides identity verification for cloudconsumers and tasks, as well as protection for data and other resources.User portal 83 provides access to the cloud computing environment forconsumers and system administrators. Service level management 84provides cloud computing resource allocation and management such thatrequired service levels are met. Service Level Agreement (SLA) planningand fulfillment 85 provide pre-arrangement for, and procurement of,cloud computing resources for which a future requirement is anticipatedin accordance with an SLA.

Workloads layer 90 provides examples of functionality for which thecloud computing environment may be utilized. Examples of workloads andfunctions which may be provided from this layer include: mapping andnavigation 91; software development and lifecycle management 92; virtualclassroom education delivery 93; data analytics processing 94;transaction processing 95; and Video Encoding/Decoding 96. VideoEncoding/Decoding 96 may encode/decode video data using delta anglesderived from nominal angles.

Some embodiments may relate to a system, a method, and/or a computerreadable medium at any possible technical detail level of integration.The computer readable medium may include a computer-readablenon-transitory storage medium (or media) having computer readableprogram instructions thereon for causing a processor to carry outoperations.

The computer readable storage medium can be a tangible device that canretain and store instructions for use by an instruction executiondevice. The computer readable storage medium may be, for example, but isnot limited to, an electronic storage device, a magnetic storage device,an optical storage device, an electromagnetic storage device, asemiconductor storage device, or any suitable combination of theforegoing. A non-exhaustive list of more specific examples of thecomputer readable storage medium includes the following: a portablecomputer diskette, a hard disk, a random access memory (RAM), aread-only memory (ROM), an erasable programmable read-only memory (EPROMor Flash memory), a static random access memory (SRAM), a portablecompact disc read-only memory (CD-ROM), a digital versatile disk (DVD),a memory stick, a floppy disk, a mechanically encoded device such aspunch-cards or raised structures in a groove having instructionsrecorded thereon, and any suitable combination of the foregoing. Acomputer readable storage medium, as used herein, is not to be construedas being transitory signals per se, such as radio waves or other freelypropagating electromagnetic waves, electromagnetic waves propagatingthrough a waveguide or other transmission media (e.g., light pulsespassing through a fiber-optic cable), or electrical signals transmittedthrough a wire.

Computer readable program instructions described herein can bedownloaded to respective computing/processing devices from a computerreadable storage medium or to an external computer or external storagedevice via a network, for example, the Internet, a local area network, awide area network and/or a wireless network. The network may comprisecopper transmission cables, optical transmission fibers, wirelesstransmission, routers, firewalls, switches, gateway computers and/oredge servers. A network adapter card or network interface in eachcomputing/processing device receives computer readable programinstructions from the network and forwards the computer readable programinstructions for storage in a computer readable storage medium withinthe respective computing/processing device.

Computer readable program code/instructions for carrying out operationsmay be assembler instructions, instruction-set-architecture (ISA)instructions, machine instructions, machine dependent instructions,microcode, firmware instructions, state-setting data, configuration datafor integrated circuitry, or either source code or object code writtenin any combination of one or more programming languages, including anobject oriented programming language such as Smalltalk, C++, or thelike, and procedural programming languages, such as the “C” programminglanguage or similar programming languages. The computer readable programinstructions may execute entirely on the user's computer, partly on theuser's computer, as a stand-alone software package, partly on the user'scomputer and partly on a remote computer or entirely on the remotecomputer or server. In the latter scenario, the remote computer may beconnected to the user's computer through any type of network, includinga local area network (LAN) or a wide area network (WAN), or theconnection may be made to an external computer (for example, through theInternet using an Internet Service Provider). In some embodiments,electronic circuitry including, for example, programmable logiccircuitry, field-programmable gate arrays (FPGA), or programmable logicarrays (PLA) may execute the computer readable program instructions byutilizing state information of the computer readable programinstructions to personalize the electronic circuitry, in order toperform aspects or operations.

These computer readable program instructions may be provided to aprocessor of a general purpose computer, special purpose computer, orother programmable data processing apparatus to produce a machine, suchthat the instructions, which execute via the processor of the computeror other programmable data processing apparatus, create means forimplementing the functions/acts specified in the flowchart and/or blockdiagram block or blocks. These computer readable program instructionsmay also be stored in a computer readable storage medium that can directa computer, a programmable data processing apparatus, and/or otherdevices to function in a particular manner, such that the computerreadable storage medium having instructions stored therein comprises anarticle of manufacture including instructions which implement aspects ofthe function/act specified in the flowchart and/or block diagram blockor blocks.

The computer readable program instructions may also be loaded onto acomputer, other programmable data processing apparatus, or other deviceto cause a series of operational steps to be performed on the computer,other programmable apparatus or other device to produce a computerimplemented process, such that the instructions which execute on thecomputer, other programmable apparatus, or other device implement thefunctions/acts specified in the flowchart and/or block diagram block orblocks.

The flowchart and block diagrams in the Figures illustrate thearchitecture, functionality, and operation of possible implementationsof systems, methods, and computer readable media according to variousembodiments. In this regard, each block in the flowchart or blockdiagrams may represent a module, segment, or portion of instructions,which comprises one or more executable instructions for implementing thespecified logical function(s). The method, computer system, and computerreadable medium may include additional blocks, fewer blocks, differentblocks, or differently arranged blocks than those depicted in theFigures. In some alternative implementations, the functions noted in theblocks may occur out of the order noted in the Figures. For example, twoblocks shown in succession may, in fact, be executed concurrently orsubstantially concurrently, or the blocks may sometimes be executed inthe reverse order, depending upon the functionality involved. It willalso be noted that each block of the block diagrams and/or flowchartillustration, and combinations of blocks in the block diagrams and/orflowchart illustration, can be implemented by special purposehardware-based systems that perform the specified functions or acts orcarry out combinations of special purpose hardware and computerinstructions.

It will be apparent that systems and/or methods, described herein, maybe implemented in different forms of hardware, firmware, or acombination of hardware and software. The actual specialized controlhardware or software code used to implement these systems and/or methodsis not limiting of the implementations. Thus, the operation and behaviorof the systems and/or methods were described herein without reference tospecific software code—it being understood that software and hardwaremay be designed to implement the systems and/or methods based on thedescription herein.

No element, act, or instruction used herein should be construed ascritical or essential unless explicitly described as such. Also, as usedherein, the articles “a” and “an” are intended to include one or moreitems, and may be used interchangeably with “one or more.” Furthermore,as used herein, the term “set” is intended to include one or more items(e.g., related items, unrelated items, a combination of related andunrelated items, etc.), and may be used interchangeably with “one ormore.” Where only one item is intended, the term “one” or similarlanguage is used. Also, as used herein, the terms “has,” “have,”“having,” or the like are intended to be open-ended terms. Further, thephrase “based on” is intended to mean “based, at least in part, on”unless explicitly stated otherwise.

The descriptions of the various aspects and embodiments have beenpresented for purposes of illustration, but are not intended to beexhaustive or limited to the embodiments disclosed. Even thoughcombinations of features are recited in the claims and/or disclosed inthe specification, these combinations are not intended to limit thedisclosure of possible implementations. In fact, many of these featuresmay be combined in ways not specifically recited in the claims and/ordisclosed in the specification. Although each dependent claim listedbelow may directly depend on only one claim, the disclosure of possibleimplementations includes each dependent claim in combination with everyother claim in the claim set. Many modifications and variations will beapparent to those of ordinary skill in the art without departing fromthe scope of the described embodiments. The terminology used herein waschosen to best explain the principles of the embodiments, the practicalapplication or technical improvement over technologies found in themarketplace, or to enable others of ordinary skill in the art tounderstand the embodiments disclosed herein.

What is claimed is:
 1. A method of video encoding a video data,executable by a processor, the method comprising: setting a first flagassociated with a current block, wherein the first flag indicateswhether a current mode is equal to a chroma from luma (CfL) mode; basedon the first flag indicating that the current mode is not equal to theCfL mode, setting a second flag associated with the current block,wherein the second flag indicates whether the current mode is equal to anominal mode of a luma block associated with the current block; settingadditional information, the additional information being one of: anindex of delta angles, one or more parameters of the CfL mode, or one ormore remaining nominal modes associated with the current block based ona value of the second flag; and encoding a chroma intra prediction modeassociated with the current block based on the first flag, the secondflag, and the additional information.
 2. The method of claim 1, whereinbased on the second flag indicating that the current mode is equal tothe nominal mode of the luma block associated with the current block,the method further comprises determining that the current mode is adirectional mode.
 3. The method of claim 2, wherein based on determiningthat the current mode is the directional mode, the additionalinformation that is signaled is the index of delta angles.
 4. The methodof claim 3, wherein contexts used to signal the index of delta anglescomprise first contexts for delta angles of luma blocks and secondcontexts for delta angles of chroma blocks.
 5. The method of claim 4,wherein the first contexts are different from the second contexts. 6.The method of claim 1, wherein based on the second flag indicating thatthe current mode is not equal to the nominal mode of the luma blockassociated with the current block, the additional information that issignaled is the one or more remaining nominal modes associated with thecurrent block.
 7. The method of claim 1, wherein based on the first flagindicating that the current mode is equal to the CfL mode, theadditional information that is signaled is the one or more parameters ofthe CfL mode.
 8. A computer system for decoding video data, the computersystem comprising: one or more computer-readable non-transitory storagemedia configured to store computer program code; and one or morecomputer processors configured to access said computer program code andoperate as instructed by said computer program code, said computerprogram code including: first setting code configured to cause the oneor more computer processors to set a first flag associated with acurrent block, wherein the first flag indicates whether a current modeis equal to a chroma from luma (CfL) mode; based on the first flagindicating that the current mode is not equal to the CfL mode, secondsetting code configured to cause the one or more computer processors toset a second flag associated with the current block, wherein the secondflag indicates whether the current mode is equal to a nominal mode of aluma block associated with the current block; third setting codeconfigured to cause the one or more computer processors to setadditional information, the additional information being one of: anindex of delta angles, one or more parameters of the CfL mode, or one ormore remaining nominal modes associated with the current block based ona value of the second flag; and encoding code configured to cause theone or more computer processors to encode a chroma intra prediction modeassociated with the current block based on the first flag, the secondflag, and the additional information.
 9. The apparatus of claim 8,wherein based on the second flag indicating that the current mode isequal to the nominal mode of the luma block associated with the currentblock, the program code further comprises determining code configured tocause the one or more computer processors to determine that the currentmode is a directional mode.
 10. The apparatus of claim 9, wherein basedon determining that the current mode is the directional mode, theadditional information that is signaled is the index of delta angles.11. The apparatus of claim 10, wherein contexts used to signal the indexof delta angles comprise first contexts for delta angles of luma blocksand second contexts for delta angles of chroma blocks.
 12. The apparatusof claim 11, wherein the first contexts are different from the secondcontexts.
 13. The apparatus of claim 8, wherein based on the second flagindicating that the current mode is not equal to the nominal mode of theluma block associated with the current block, the additional informationthat is signaled is the one or more remaining nominal modes associatedwith the current block.
 14. The apparatus of claim 8, wherein based onthe first flag indicating that the current mode is equal to the CfLmode, the additional information that is signaled is the one or moreparameters of the CfL mode.
 15. A non-transitory computer readablemedium having stored thereon a computer program for decoding video data,the computer program configured to cause one or more computer processorsto: set a first flag associated with a current block, wherein the firstflag indicates whether a current mode is equal to a chroma from luma(CfL) mode; based on the first flag indicating that the current mode isnot equal to the CfL mode, set a second flag associated with the currentblock, wherein the second flag indicates whether the current mode isequal to a nominal mode of a luma block associated with the currentblock; set additional information, the additional information being oneof: an index of delta angles, one or more parameters of the CfL mode, orone or more remaining nominal modes associated with the current blockbased on a value of the second flag; and encode a chroma intraprediction mode associated with the current block based on the firstflag, the second flag, and the additional information.
 16. Thenon-transitory computer readable medium of claim 15, wherein based onthe second flag indicating that the current mode is equal to the nominalmode of the luma block associated with the current block, the computerprogram configured to further cause one or more computer processors todetermine that the current mode is a directional mode.
 17. Thenon-transitory computer readable medium of claim 16, wherein based ondetermining that the current mode is the directional mode, theadditional information that is signaled is the index of delta angles.18. The non-transitory computer readable medium of claim 17, whereincontexts used to signal the index of delta angles comprise firstcontexts for delta angles of luma blocks and second contexts for deltaangles of chroma blocks.
 19. The non-transitory computer readable mediumof claim 18, wherein the first contexts are different from the secondcontexts.
 20. The non-transitory computer readable medium of claim 15,wherein based on the second flag indicating that the current mode is notequal to the nominal mode of the luma block associated with the currentblock, the additional information that is signaled is the one or moreremaining nominal modes associated with the current block.